Such electric fuel pumps have long been known, and are frequently provided with a mechanically commutated direct-current motor.
There are also known pumps which are driven by an electronically commutated direct-current motor, although they are used only for pumping cooling water and similar liquids and are referred to as "canned" pumps (German Patent Application DE 195 45 561 A1). The main purpose of the "can" is to seal the pump compartment from the outside.
In German Patent Application DE 42 22 394 A1 there is shown a pump-motor unit in which a cooling wall is provided between the pump mechanism and the drive motor and at the cooling wall there is disposed means for cooling at least one power part of a speed controller of the motor.
In German Patent Application DE 43 31 803 A1 there is shown an electronically commutated electric motor for the drive of a liquid feed pump, with means for holding the permanent magnets around the rotor. Therein, the current leads connected to the stator winding can be connected to an electronic commutation device, which is not mounted directly on the electric motor and is external to the electric pump.
There exists a need, however, for fuel pumps which can be driven by electronically commutated direct-current motors, and which overcome the problems presently preventing widespread use.